It has been the practice in the past to stop the press for at least ten minutes while physically changing the plunger. This would involve the positioning of hoist equipment into proximity to the press where there is considerable heat present. The workers would have to release the old plunger while supporting with the hoist. Cooling water inlet and outlet lines to the plunger would have to be disconnected and the plunger moved away from the area. The new plunger would then be brought in on a hoist and attached to the plunger assembly and the cooling water inlet and outlet lines would be reconnected. This was a time consuming operation and after the replacement had been made, it would take at least 20 more minutes for the molds to become reheated, with gobs of molten glass, to the required temperature to begin producing acceptable face plates or glass parts.
When considering that these plungers are around 700 pounds, it can be seen that it is a major interruption of the forming process when it is necessary to change the plunger. The one-half hour loss of production is costly, as well as the necessity of restarting a glass forming system that requires being brought back into thermal equilibrium after the interruption.
In view of the foregoing, it is an object of the present invention to provide a system that will remove an old plunger and replace it with a new plunger without requiring an operator to actually approach the machine any closer than five feet.
It is a further object of the invention to provide a plunger handler that will support a new plunger and receive an old plunger as it is released from the press and then reverse the positions of the old and new plunger to permit the accurate replacing of the new plunger in the plunger holder of the press without stopping the movement of the mold supporting table so that those articles that have been previously pressed may continue through their cycle of cooling while the plunger is being replaced.
It is a further object of the invention to provide a plunger holder and clamping mechanism that will release a plunger to a plunger change support holder that will not disturb the continuation of the machine and permit the insertion of a new plunger in the precise position where the cooling water system will be reconnected without requiring any further manipulation and only require the shutting off of the water supply during the actual replacement of the plunger.
It is a still further object of the invention to provide plunger change equipment that is retracted out of the way during normal operation of the press and then be moved into position and loaded with a new plunger to be inserted in a plunger holder after the old plunger is received and supported by change equipment with the water shut-off, gob feeding diversion and change equipment movement under the control of a series of switches and motors which control the entire sequence of operation of the plunger exchange with only a minimum of operator intervention.
Other objects and advantages will be apparent from the following description taken in conjunction with the annexed sheets of drawings.